 /*******************************************************************************
  * Copyright (c) 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.dialogs;

 import java.text.BreakIterator ;
 import java.util.Collection ;
 import java.util.HashMap ;
 import java.util.Iterator ;
 import java.util.Map ;

 import org.eclipse.jface.preference.IPreferenceNode;
 import org.eclipse.jface.viewers.ITreeContentProvider;
 import org.eclipse.jface.viewers.TreeViewer;
 import org.eclipse.jface.viewers.Viewer;
 import org.eclipse.ui.internal.preferences.WorkbenchPreferenceExtensionNode;

 /**
  * A class which handles filtering preferences nodes based on a supplied
  * matching string.
  *
  * @since 3.1
  *
  */
 public class PatternItemFilter extends PatternFilter {

     /**
      * this cache is needed because
      * WorkbenchPreferenceExtensionNode.getKeywordLabels() is expensive. When it
      * tracks keyword changes effectivly than this cache can be removed.
      */
     private Map keywordCache = new HashMap ();

     protected boolean matchItem;

     /**
      * Create a new instance of a PatternItemFilter
      *
      * @param isMatchItem
      */
     public PatternItemFilter(boolean isMatchItem) {
         super();
         matchItem = isMatchItem;
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.jface.viewers.ViewerFilter#select(org.eclipse.jface.viewers.Viewer,
      * java.lang.Object, java.lang.Object)
      */
     public boolean select(Viewer viewer, Object parentElement, Object element) {

         ITreeContentProvider contentProvider = (ITreeContentProvider) ((TreeViewer) viewer)
                 .getContentProvider();

         IPreferenceNode node = (IPreferenceNode) element;
         Object [] children = contentProvider.getChildren(node);
         String text = node.getLabelText();

         if(wordMatches(text))
             return true;
         
         if (matchItem) {

             // Will return true if any subnode of the element matches the search
 if (filter(viewer, element, children).length > 0)
                 return true;
         }

         if (node instanceof WorkbenchPreferenceExtensionNode) {
             WorkbenchPreferenceExtensionNode workbenchNode = (WorkbenchPreferenceExtensionNode) node;

             Collection keywordCollection = (Collection ) keywordCache.get(node);
             if (keywordCollection == null) {
                 keywordCollection = workbenchNode.getKeywordLabels();
                 keywordCache.put(node, keywordCollection);
             }
             if (keywordCollection.isEmpty())
                 return false;
             Iterator keywords = keywordCollection.iterator();
             while (keywords.hasNext()) {
                 if (wordMatches((String ) keywords.next()))
                     return true;
             }
         }
         return false;

     }

     /**
      * Return whether or not if any of the words in text satisfy the
      * match critera.
      * @param text
      * @return boolean <code>true</code> if one of the words in text
      * satisifes the match criteria.
      */
     private boolean wordMatches(String text) {
         
         //If the whole text matches we are all set
 if(match(text))
             return true;
         
         // Break the text up into words, separating based on whitespace and
 // common punctuation.
 // Previously used String.split(..., "\\W"), where "\W" is a regular
 // expression (see the Javadoc for class Pattern).
 // Need to avoid both String.split and regular expressions, in order to
 // compile against JCL Foundation (bug 80053).
 // Also need to do this in an NL-sensitive way. The use of BreakIterator
 // was suggested in bug 90579.
 BreakIterator iter = BreakIterator.getWordInstance();
         iter.setText(text);
         int i = iter.first();
         while (i != java.text.BreakIterator.DONE && i < text.length()) {
             int j = iter.following(i);
             if (j == java.text.BreakIterator.DONE)
                 j = text.length();
             if (Character.isLetterOrDigit(text.charAt(i))) {
                 String word = text.substring(i, j);
                 if (match(word))
                     return true;
             }
             i = j;
         }
         return false;
     }

 }

